It is known to process a semiconductor substrate to achieve a dry and low-contamination condition after processing steps such as chemical mechanical polishing (CMP) and scrubbing. It has also been proposed to employ immersion drying to semiconductor substrates using the so-called Marangoni effect. An example of a Marangoni dryer is disclosed in co-pending, commonly-owned U.S. provisional patent application Ser. No. 60/335,335, filed Nov. 2, 2001, entitled “Single Wafer Immersion Dryer and Drying Methods”, and which is hereby incorporated herein by reference in its entirety.
In Marangoni drying, a substrate is raised in a vertical orientation from a fluid bath, and an alcohol vapor is delivered to a meniscus that is formed at the substrate/fluid interface. The alcohol vapor reduces the surface tension at the meniscus, thereby creating a “Marangoni” force resulting in a downward liquid flow opposite to the substrate lift direction. As a result, the substrate surface above the meniscus is dried.
Marangoni drying is promising in terms of substrate throughput, absence of water marks, and low contamination levels achieved. However, it would be desirable to achieve comparable results without the inconveniences of delivering and exhausting hazardous alcohol vapor.